The visionaries: Meet the men who predicted the crash

The rogue trader: Nassim Nicholas Taleb

An applied statistician and derivatives trader-turned-philosopher, Taleb, 48, is author of The Black Swan: The Impact of the Highly Improbable (Penguin, £8.99)

I predicted the current global financial crisis in my last book, The Black Swan. You might well ask why more people didn't see it coming. Well, there are some situations where the outcome is predictable – if you board a plane being flown by a drunk pilot, it's significantly more likely to crash. But there are rarer events, such as the current financial turmoil, that have complicated probabilities we can't compute. The problem comes when people make claims about these probabilities; what they say may sound convincing, but the point about these probabilities is that it's difficult to offer any sort of certainty. The disastrous results can be seen in financial markets the world over.

My predictions have been built on a philosophy I have preached for two decades: that we should avoid risks we don't properly understand. Ever since the Enlightenment we have based our actions on what we think we know. I'm trying to reverse this philosophy, to encourage people to make decisions based on what they don't know, on realising their lack of information. No one believed that black swans existed until they were found in Australia, which is why I borrowed the term for exceptional, unpredictable events which have a great impact.

As we survey the wreckage of the world's financial systems, this philosophy may sound obvious. But, until recently, I was a lone voice. I tried to pursue my thesis in academia but I realised I was an outsider. Fortunately for me, I was also a trader in the stock markets. Those traders who were betting on market stability and growth found it easier than I to attract investors, but nevertheless, in 1987 I managed to derive enough income from the stock-market crash of that year to be independent for life.

Despite now feeling vindicated in my beliefs, I harbour a lot of bitterness. I wrote in The Black Swan that you need a constituency around you to share your opinions, and I didn't have that in my academic pursuits. But that's what happens when you try to tell people the sky is blue and they're convinced it's yellow because they read it in the Wall Street Journal or were told so by a Nobel Prize-winning economist. Interestingly, I didn't suffer much from public attacks; rather, I received huge amounts of hate mail from the economics establishment. But it convinced me that I was right – why would they be so angry if I wasn't?

You have to be of a certain temperament to follow my course of action, have a capacity for loneliness. Before I wrote Fooled by Randomness in 2001, I was presenting my ideas in ways that were inaccessible to a broad readership: academic papers stay within a small community of people. But my isolation forced me to present my ideas in a book that would be more accessible. The result was The Black Swan, and I certainly feel vindicated by its success.

People think that being embraced by others for your beliefs shouldn't matter – let me tell you, it's exhilarating. In the past I wouldn't have been reviewed by people such as the renowned historian Niall Ferguson; he is now a friend and we've worked together. And the King of Sweden has invited me to be part of a task force on global warming.

If I'm beginning to sound like the sort of figure I've spent my career criticising – the guru – there's a key distinction: I say listen to negative rather than positive advice. When you go to a book store there are plenty of publications telling you how to get rich, but none telling you how not to go bankrupt. To put it another way, if you want to get rich, avoid being poor. Negative advice is more robust than positive advice; it is rarely respected, though, unless you present it in a digestible form. For instance, various journalists recently asked me my opinion of the financial crisis, and I said I didn't know. All I said is that the banks are being piloted by people who know a lot less about the risks than they think they do. That's negative advice.

I haven't been surprised by the past few weeks of financial turmoil. I warned about a bail-out with tax-payers' money. But nobody likes to be reminded of this. (A Swiss banker recently told me I was so right that had I lived in medieval Europe, I'd have been burnt at the stake.)

I don't know if I'm a visionary; I'm just someone with a consistent view of the world. Since the crash of 1987, my message is that we have to learn to live in a world we don't understand. We mustn't listen to the pressures of the market because the market doesn't work. And every time we interfere with it, we're going to get in trouble.

The lingerie liberator: Serena Rees

Rees, 40, is co-founder of the luxury lingerie brand Agent Provocateur, which opened its first branch in Soho in 1994

Before we opened, the lingerie market was depressing. On the one hand you had retailers such as Marks & Spencer, where you were left to wade into a big sea of mass-produced, machine-washable underwear without anyone to advise you; and on the other you had sex shops, where things were exciting but cheap. "Sexy" underwear in those places wasn't sexy, it was more of a joke, and no women would have gone in there anyway. The odd boutiques that did exist tended to be run by matronly women who told you what to wear, and it was never anything remotely scanty or adventurous.

There were some who questioned whether a market existed for anything different, but I knew simply from my own experience that I wanted something else. I always had to go out of my way to find beautiful, glamorous lingerie and that provided enough inspiration for Joe [Corre, her former husband and business partner] and I to imagine a place like Agent Provocateur, where women could go to for a quality product and an honest, specialist experience. We weren't just selling knickers; we were teaching how to be a woman, how to feel and act differently.

I think what we did was put fashion into lingerie, and personality and luxury into the retail experience. It's made everyone else sit up and realise how rubbish their own lingerie departments really were, because in the past 14 years every single department store around the globe has asked us to help revamp them. Now when you walk into these places, you have the same choice in underwear that exists in clothes or shoes. '

The keyhole evangelist: Lord Ara Darzi

Born in Iraq, Darzi, 48,emigrated to Ireland at 17 to study medicine, before moving to London, where he began his pioneering work on keyhole surgery in 1990. Now a Labour health minister, he has been charged with reforming the NHS in England. He still conducts operations at St Mary's in London

I developed the keyhole technique during an era when, from a surgical perspective, the bigger the incision, the more macho the surgeon. I recognised that an incision was probably the biggest component of pain for a patient in an operation, so what was driving me was how to reduce that.

I started with keyhole operations for gall-bladder surgery and you could see patients recovered much quicker. I had a lot of critics, including in my own team – my superior at the Central Middlesex initially pronounced the procedure dangerous – so I had to turn them around. You bring people with you not by saying "because I say so", but by taking them through the entire process, so that when it's finished, they themselves come and tell you it's better.

I worried I'd be singled out as a maverick, but I always remembered why I was doing it: not to be different but because it had an impact on the care of my patients. I pushed the boundaries in using keyhole surgery for more advanced procedures, from hernia repairs to treating bowel cancer. The more I published about the subject, the more patients expressed a desire to have their procedure done that way and 15 years on, it has become common practice in a wide range of procedures. And there's nothing more gratifying than knowing I've contributed to something that has had a big impact on patients' wellbeing.

The crash survivor: Peter Hambro

The 63-year-old is a scion of the famous Hambro banking dynasty. He is executive chairman of Peter Hambro Mining, the second-biggest gold producer in Russia, and has warned against the dangers of financial derivatives for over a decade

My father was in the gold business before me; the stuff flows through my veins. Gold is a proven long-term store of value: if you own an ounce you wouldn't have to worry which bank it is in; you'd have it in your pocket.

When I left gold trading and bought a Russian gold mine 15 years ago, people said I was mad, but I invested in it partly because I thought it would make a lot of money and partly because I was terrified about a collapse in the financial markets. I have always thought that the lack of regulation in the mark-to-market derivatives industry in the mid-1990s was a recipe for disaster. I wrote to the Governor of the Bank of England to tell him so. I felt that Gordon Brown's sale in 1999 of half of the country's gold reserves at $256 an ounce was an error. I became convinced that the country's gold would be needed as a reserve asset and that its price would rise, and I've been proved right – gold has gone from $300 an ounce a decade ago to $830 an ounce now.

I was lucky enough to have family members old enough to have lived through the crash of the 1920s and so to have discussed this with them. Perhaps for that reason I had a stronger feeling than most that things were going wrong. '

The organic guru: Craig Sams

Born on a farm in Nebraska in the US, Sams, 63, is the co-founder of Whole Earth Foods and Green & Black's Organic Chocolate. He opened the UK's first macrobiotic restaurant and shop in 1969 and co-edited and published Seed, The Journal of Organic Living, from 1971 to 1977. He is currently vice-chairman of the Soil Association

My take on eating has always been macrobiotic: the principle that you eat with justice and actually benefit from eating less and lower down the food chain. I'd been travelling in India in early 1965 and I'd come back pretty weak with dysentery and hepatitis. Some friends in Philadelphia had adopted this diet and it appealed to me because I liked its libertarianism.

When I started eating this way the difference was marked, in that I felt normal and not weak or grumpy. By the late-1960s, my brother and I had moved to London and gone into business with an organic restaurant, shop and magazine. We were so far ahead of the curve: by 1974 there were 350 shops in the UK based on ours on Portobello Road in west London. Having said that, we thought that everyone would want in within a year or two. Forty years later, we're still not there yet. My brother Greg says we could see the future, but we were looking the wrong way through the telescope.

Some businesses have fared better than others. There were times when other people were buying brown rice from us, repackaging it and undercutting us with our own rice. We learnt how important it was to build a brand. Whole Earth, for example, was based on recipes – we made the best; so we were not just first, we were conscientiously good.

There were a lot of people around that time who took Timothy Leary too seriously. I'd been to business school in America, so I had that entrepreneurial spirit. Tony Elliott [founder of Time Out], Richard Branson, [the publishing mogul] Felix Dennis – all more successful and prosperous than me – went off and didn't do what their education had brought them up to do, because something in the mid-1960s derailed them. We started businesses that catered to like-minded people but reached out to a wider audience.

It's a myth that organic food is some kind of middle-class affectation. Our core were squatters, drop-outs and hippies, but we also got the Holland Park set and people like Terence Stamp pulling up in their Daimlers. I suppose you could say we started off by catering to the extremes.

The fashion first: Barbara Hulanicki

Hulanicki, 72, set up Biba in the early-1960s with her husband Stephen "Fitz" Fitz-Simon as a mail-order business. She opened her first shop, in London's Kensington, in 1965. The Biba model – affordable, edgy fashion for the masses, short runs on each design, pop music in-store, instantly recognisable branding – is what high-street behemoths such as Topshop and H&M were built on

Before Biba, you couldn't buy stylish, affordable clothes. There was Jean Muir and Mary Quant, but they were terribly expensive. No one was selling clothes for young secretaries who had rent to pay. On the high street you had C&A (horrible), Woolworths or Marks & Spencer. We were young and wanted fashion, but the design at these shops wasn't done by fashionable designers; it tended to be done by the managing directors' wives. What we pioneered was respect for the designer.

At first the suppliers thought we were mad. I got in this company that made rugby shirts and asked them to make them skinny-fit. These two salesmen roared with laughter. A week later, as we re-ordered, they came back cap in hand.

Before we opened our shop in High Street Kensington, no one went there. It was just decaying old department stores – but Fitz said not to worry; if we were by the Tube, people would come. He was right.

We pioneered branding, too: our partners, later on, kept complaining, "Why do you have to have everything black and gold, why always the same logo?" Now, suddenly, brands are valuable. We had no idea of that, I just wanted everything to look like it was from the same stable.

Mothers hated us – they thought the music was too loud: music in shops was completely new too. We were also the first to put co-ordinating shoes, tights and make-up in the same place. None of it was strategic – it just evolved organically. It was the same when we started selling baby clothes, things for boys and stuff for the home.

When I go to Oxford Circus and look at H&M and Topshop – all those big chain stores doing the same things – I love it. I think, "We were right after all." '

The childbirth crusader: Wendy Savage

Savage, 73, became London's first woman to be appointed an obstetrics and gynaecology consultant when she joined the London Hospital Medical College in 1977. Her anti-interventionist views and a belief that decision-making during childbirth should be in the hands of the women giving birth, led to her suspension in 1985 under false charges of incompetence. She was reinstated the following year, by which time her case had become a cause célèbre. She is the author of several books, including A Savage Enquiry (1986)

The idea of a woman being in control of her own birth was a concept that just wasn't around when I was a medical student back in 1958. The doctors and midwives were in charge and the woman would hand herself over to them. But I felt it was a woman's right to choose how she gave birth. If a woman said to me. "I want to have my baby at home," and if she was suitable and healthy, I would say, "Fine". My approach upset a lot of people, but I didn't think I'd put my head above the parapet until I got suspended; it was a terrible shock.

I was accused of incompetence in the management of five births – four of which were Caesarean sections, which I'd been reluctant to do, so I was accused of putting these lives in danger. I became a huge cause célèbre; people all over the country wrote and sent money for my defence fund. My suspension opened up an area for debate that hadn't been on the media radar at the time.

Things are a lot better than they were: last year the Healthcare Commission's largest ever survey found that 90 per cent of women are now satisfied with their care. But it's not perfect. I've spent years fighting for a woman's right to choose an abortion, but [with the rise in Caesareans] I find myself saying I don't think they have a right to choose a Caesarean. I think if a woman is given the real facts – that it is a major operation and it's much easier to care for a baby if you give birth naturally – they'd agree that unless strictly medically necessary it's the last thing you need.

The eco-visionary: Sir Crispin Tickell

A diplomat, academic and soldier, Tickell, 78, has shoehorned several careers into his CV, but his lasting legacy is as a self-taught environmentalist and author of the influential Climate Change and World Affairs, which introduced the idea of human-induced global warming in the 1970s

We are undergoing seismic changes and it's been nice to be an unorthodox voice. I studied history as an undergraduate and was convinced it was only a fraction of the issues I should be interested in. Kings and queens were the froth on top of the big stuff, like disease and migration. So I started looking at the impact of climate change on world affairs.

During a fellowship at Harvard University in 1976 I took a course in climatology at MIT. That was when you could read everything on the subject in three months. In 1977 my book, Climate Change and World Affairs, was published. Reaction to it was interesting. In the political world it worked well. But in the scientific world there was the feeling that "This chap isn't a scientist, who is he to lecture us?" Most scientists believed climate change was a very slow process, which I thought was nonsense. I think the scientific community felt that I had leaped into their territory but time has shown they got it wrong, not me. A lot of people thought I was a bit of a nutcase but I was prepared for that. I was sure that people were listening to me but I knew that I didn't have a prescription to offer.

Most importantly, I suggested that Margaret Thatcher raise the issue of climate change at the 1984 G7 Summit. The Americans were on board at the beginning; it wasn't until George W Bush took over that attitudes became polarised – but that will change.

It has been a strength not to come from a scientific background; I was better equipped to look at the political dimension of the problem. Do I feel I should be slowing down? No, things are just too interesting to miss right now.

The hi-tech pioneer: Jim Westwood

From 1963 to 1990, Westwood, 60, was Sir Clive Sinclair's right-hand man, and the inventor of the first pocket calculator, the first portable, flat-screened television and the first affordable home computer, the ZX Spectrum

The first thing we wanted to do was make a tiny TV. From 1964 that was the burning ambition. We exhibited one at a trade fair in 1966. It went to prototype, but it was before its time. We could design it, but could we mass-produce it? No.

We launched portable televisions in 1973 and 1978. The first one was more than £200 and the second more than £100, but we needed a price nearer £50. The final throw of the dice was in 1983. That was a flat-screen television using a flat cathode-ray tube – but the tubes we intended to manufacture for £2 each actually cost £10 each. That was a problem. It was impossible to get the price low enough. We'd worked on televisions for 20 years and I thought I had it cracked, so it was a bit sad.

But we'd already started to do something else: computers. The ZX80 and ZX81 were the first sub-£100 computers. They were very successful. The ZX Spectrum sold 3.5 million units. We wanted to produce a tool to help people understand computers. Instead, people played games on them.

Out of 20 ideas we had, three would hold water and one would make it. My favourite idea was the pocket calculator. I had found a way to reduce the energy consumption to a 30th of existing calculators, so you could have smaller batteries. The Sinclair Executive was the first pocket calculator, but by 1979 we had moved out of calculators: the Japanese made it cheaper to buy a complete calculator than buy its components and assemble it in Europe.

And that is what my life has been like with Clive; making a brilliant idea saleable. You find a trick but other people will catch up with it. It's always a race.